let the random subsystem read the tsc for event "timestamps".

2 files changed, 11 insertions, 12 deletions

diff --git a/sys/arch/amd64/amd64/machdep.c b/sys/arch/amd64/amd64/machdep.c
index fe16af19570..9dab8947af0 100644
--- a/sys/arch/amd64/amd64/machdep.c
+++ b/sys/arch/amd64/amd64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.266 2020/05/31 06:23:56 dlg Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.267 2020/06/03 06:54:04 dlg Exp $	*/
 /*	$NetBSD: machdep.c,v 1.3 2003/05/07 22:58:18 fvdl Exp $	*/
 
 /*-
@@ -2055,12 +2055,3 @@ check_context(const struct reg *regs, struct trapframe *tf)
 
 	return 0;
 }
-
-unsigned int
-cpu_rnd_messybits(void)
-{
-	struct timespec ts;
-
-	nanotime(&ts);
-	return (ts.tv_nsec ^ (ts.tv_sec << 20));
-}
diff --git a/sys/arch/amd64/include/cpu.h b/sys/arch/amd64/include/cpu.h
index 95f715d5e0f..5a76eb21e3c 100644
--- a/sys/arch/amd64/include/cpu.h
+++ b/sys/arch/amd64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.136 2020/05/31 06:23:56 dlg Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.137 2020/06/03 06:54:04 dlg Exp $	*/
 /*	$NetBSD: cpu.h,v 1.1 2003/04/26 18:39:39 fvdl Exp $	*/
 
 /*-
@@ -304,7 +304,15 @@ void cpu_unidle(struct cpu_info *);
 #include <machine/cpufunc.h>
 #include <machine/psl.h>
 
-unsigned int cpu_rnd_messybits(void);
+static inline unsigned int
+cpu_rnd_messybits(void)
+{
+	unsigned int hi, lo;
+
+	__asm volatile("rdtsc" : "=d" (hi), "=a" (lo));
+
+	return (hi ^ lo);
+}
 
 #endif /* _KERNEL */